Tweezers Research Articles

“Tweezer Clock” Offers New Possibilities in Timekeeping

“Tweezer Clock” Offers New Possibilities in Timekeeping

Custom Made Versatile Device: A Modified Tweezer for Multiple uses in Clinical Orthodontics:

Custom Made Versatile Device: A Modified Tweezer for Multiple uses in Clinical Orthodontics:

An experimental study of rabbits with liver cancer treated with sorafenib combined with transcatheter arterial chemoembolization

Objective To study the curative effect of sorafenib combined with transcatheter arterial chemoembolization (TACE) on rabbit liver cancer model. Methods VX-2 tumor tissues were directly implanted with microscopic tweezers. 20 rabbits were randomly divided into the experimental group and the control group. TACE was performed at 21 days after modeling. The experimental group was treated with intragastric administration of sorafenib after operation, while the control group was treated with intragastric administration of the same dose of normal saline, for 14 days. Levels of alanine aminotransferase (ALT) and total bilirubin (TBIL), tumor volume, vascular endothelial growth factor (VEGF) and microvessel density (MVD, achieved by staining CD34 cells) were determined and compared between both groups. Results The levels of ALT and TBIL in both groups were significantly increased at 3 days and 14 days after operation (P<0.05). The above levels in the experimental group were significantly lower than those in the control group (P<0.05). The tumor volume in the experimental group at 7 and 14 days after operation [(1.70±0.25) cm3 and (1.75±0.26) cm3] was significantly smaller than that in the control group [(2.12±0.32) cm3 and (3.04±0.42) cm3] (P<0.05). The expression levels of VEGF and CD34 in the experimental group on the 21st day after operation [(5.18±0.75) and (31.46±4.25)] were significantly lower than those in the control group [(6.46±0.87) and (61.28±8.40)] (P<0.05). Conclusion Sorafenib combined with TACE is effective in the treatment of rabbit VX-2 liver cancer. It can significantly inhibit the expression of VEGF and decrease the MVD. Key words: Liver cancer; Animal experiment; Sorafenib; Hepatic artery embolization

Clinical efficacy of low-temperature plasma radiofrequency ablation under endoscope-supported laryngoscope in the treatment of adult patients with laryngeal papilloma

Objective To investigate the clinical effect of low-temperature plasma radiofrequency with endoscopic laryngoscope in the treatment of adult patients with laryngeal papilloma. Methods From January 2014 to April 2018, 60 adult patients with laryngeal papilloma in Zhuji Central Hospital were enrolled in this study.According to the treatment methods, they were divided into control group and observation group, with 30 cases in each group.The control group was treated with laryngoscope tweezers, and the observation group was treated by low temperature plasma radiofrequency with endoscopic laryngoscope.The operation time, intraoperative blood loss, hospitalization time and postoperative complications were recorded.The follow-up was performed on the first day after operation.The recurrence rate and average recurrence time were recorded. Results The average operation time in the observation group was (29.54±4.52)min, which was significantly shorter than (38.85±5.47)min in the control group(t=7.186, P=0.000). The intraoperative blood loss of the observation group was (1.24±0.76)mL, which was significantly lower than (35.69±5.88)mL of the control group(t=31.825, P=0.000). The length of hospital stay of the observation group was (3.83±1.17)d, which was significantly shorter than (4.79±1.47)d of the control group(t=2.798, P=0.006). The incidence rate of postoperative complication in the observation group was 3.33% (1/30), which was significantly lower than 23.33% in the control group (χ2=5.192, P=0.022). The mean duration of postoperative recurrence in observation group was (2.42±0.57)months, which was significantly longer than (1.28±0.36)months in the control group(t=9.261, P=0.000). The postoperative recurrence rate of the observation group was 6.67% (2/30), which was significantly lower than that of the control group [40.00%(12/30), χ2=9.316, P=0.002]. Conclusion Low temperature plasma radiofrequency with endoscopic laryngoscope in the treatment of adult patients with laryngeal papilloma has less trauma, and can extend the recurrence time, reduce the postoperative recurrence rate. Key words: Laryngeal diseases; Papilloma; Laryngoscopy; Low temperature plasma radiofrequency; Adult

A New Self-Complementary Bis-Acridinium Tweezer

A New Self-Complementary Bis-Acridinium Tweezer

Measuring the Reaction Rates of High Affinity Reactions by Single-molecule Magnetic Tweezers†

Measuring the Reaction Rates of High Affinity Reactions by Single-molecule Magnetic Tweezers†

Linewidth of femtosecond laser two-photon processing considering optical tweezers

In this paper, the linewidth of femtosecond laser two-photon polymerization is studied by the theory of free radical density and the effect of optical tweezers. Based on the relationship between free radical density and time in the process of two-photon polymerization, the expression of linewidth of two-photon femtosecond laser processing is deduced considering the effect of optical tweezers. The relationship of linewidth with scanning speed and laser power is studied and the influence of different light initiators on the linewidth is also discussed. The theoreticial result agrees well with the experimental one in the literature. The result of this paper gives a new idea for the study of femtosecond laser two-photon processing, and provides a theoretical formula for the study of the influence of optical tweezers on linewidth.

In vitro cultive of cedar with supplementation of the PDA culture media

The presente study had as finality to evaluate the germination of cedar seeds in vitro in PDA culture media. The experiment was realized on the Vegetable Biotechnology laboratory of FACC – Faculdade de Concordia/SC. For the procedure, 200g of english potato were used, put on boiling process for 20 minutes in 1L of distilled water, next, the broth of this solution was used. 20g of saccharose ans 12g of agar were added on it, pH adjusted in 5,8, and 8mL distributed on test tubes, totalizing 40 tubes taken to autoclaving process along with tweezers, distilled water and others, immersed for 75 minutes in sodium hypochlorite (2,5% v/v), and after that the inoculation process on the culture media was realized. The feature evaluated on this experimente was the possible germination of cedar seeds in PDA culture media. The cultures were mainteined on growing room with controled temperature of 25 ± 2oC, under photoperiod of 16 hours, provided by fluorescente lamps Philips TDL (22.3 µmol.m - ².s - ¹) and relative humidity of 70%. The results demonstrated 80% of seeds germination. Yet, it’s interesting to work with PDA culture media for cedar seeds germination.

DYNAMICAL PROPERTIES OF PLASMID DNA MOLECULE IN PULSE REGIME BY OPTICAL TWEEZERS

The dynamical properties of the plasmid DNA molecule in the optical tweezers using pulsed Gaussian laser beam is investigated. The finite difference Langevin equation (FDLE) describing the dynamics of polystyrene microsphere linking to plasmid DNA molecule is presented. This FDLE is numerically solved to discuss the influence of parameters of pulsed Gaussian laser beam as peak intensity, duration on the dynamical properties of polystyrene microsphere. From the variances of position, velocity or all forces in pulsing time, the conditions to stretch a plasmid DNA molecule into stretching state, where the maximum stretched length is about its contour length are discussed and found out.

DYNAMICS OF POLYSTYRENE MICROSPHERE LINGKING TO λ-PHAGE DNA MOLECULE IN OPTICAL TWEEZERS USING PULSED GAUSSIAN LASER BEAM

The trapping process of the biological micro-particle in the tweezers using CW laser beam has been investigated in series of our works. In the CW regime, the dynamics of polystyrene microsphere linking to λ-phage DNA molecule depending on the optical force, Brown force and its elastic force are simulated and discussed. In this paper we present the finite difference Langevin equation (FDLE) describing the dynamics of trapped bead linking to DNA molecules in an optical tweezers. Using FDLE the dynamics, i.e., the position-time characteristics of polystyrene microsphere linking to λ-phage DNA molecule are simulated in the pulse regime. The obtained results show that all principle parameters as the peak intensity, beam waist radius, and duration of pulsed Gaussian laser beam, well as the setting-up position of DNA molecule influence on the dynamics, especially on the “pulling” and “stability” times of trapped bead. The conditions for λ-phage DNA molecule in stretching state are discussed for experimence.

STRETCHING PROCESS OF PLASMID DNA MOLECULE IN OPTICAL TWEEZERS USING CW GAUSSIAN LASER BEAM

The trapping dynamics of plasmid DNA molecule linking to polystyrene microsphere (trapped bead) in optical tweezers are investigated in the CW regime using the finite difference Langevin equation (FDLE). The obtained results show that, due to the extension of DNA moleucle, the stretching process characterizing by its pulling time, and stretched length depend on the peak intensity of laser beam and its initial position. The conditions to stretch plasmid DNA molecule in stretching state are discussed and the threshold value of energy of lase beam is found out and compared to that of λ-phage DNA moeucle

Polygonal micro-whirlpools induced in ferrofluids

We report on the observation of the polygonal whirlpools in the thin layer of ferrofluid under illumination with a laser beam carrying optical vortex and in the presence of a vertical magnetic field. This kind of structures have attracted attention after discovering a hexagonal storm in Saturn’s atmosphere. Our polygonal whirlpools were created in a closed system (no free surfaces) in micro-scale (whirlpool diameter <20 μm) by the use of holographic optical tweezers. The polygonal shape was changed by varying the magnetic field strength or value of the optical vortex topological charge.

单个大鼠胎肝干细胞的激光光镊喇曼光谱

Laser tweezers Raman spectroscopy system is an optical technique combining the laser tweezers and Raman spectroscopy technique,which could be able to study recognition and detect constituent components of single biological cell in close to its natural state.Rat fetal liver stem cells at 10~21days of gestation and adult rat hepatocytes were separated by collagenase digestion.Single fetal liver stem cell,hepatocyte and WB-F344rat liver stem cell line were detected by laser tweezers Raman spectroscopy technique,and their Raman spectrum was compared.It was indicated that the value of 1 336cm-1(assigned to Polynucleotide chain,DNA-purine bases)and 1 446cm-1(CH2bending mode of proteins)band increased before 13th day and decreased after 14th day of gestation,and the mean of peak value of1 336cm-1 and 1 446cm-1 bands at 13th day of gestation was the highest.The results showed that the Laser tweezers Raman spectroscopy system could differentiate fetal liver stem cells of different period of gestation from adult hepatocytes,and analyze differentiation and development mechanism of fetal liver stem cells,which lay a foundation for clinical application of hepatic stem cells therapy.

Spectral analysis by a video camera in a holographic optical tweezers setup

We discuss the basic parameters of the holographic tweezers equipped with a diode laser and cheap video camera. We compare these parameters with the system using a fast camera and high power Nd:YAG laser. The measured parameters are: the power spectra density calculated from tracing the position of the micron polystyrene beads and the trap stiffness. We show that this cheap optical tweezers system is sufficient for experiments in microbiology.

利用光镊计算工具箱实现光镊系统的参量评价

Because the diameter of the trapped sphere obtained by the optical tweezer usually locates in the intermediate range,theoretical calculation was difficult.OTT1 optical tweezers computational toolbox is a kind of T matrix method based on the GLMT theory.The development of the OTT1 optical tweezers computational toolbox makes detailed calculation and evaluation feasible.In this paper,the optical trapping coefficiency curve,its linearity and stiffness,and the interchangebility of Duke series polystyrene sphere were calculated and evaluated.The results show that when the numerical aperture becomes closer to the refractive index of water,a better trapping effect will be achieved;when an 800~1 200 nm polystyrene sphere is trapped,the stiffness of optical tweezers is larger;when a PS sphere with diameter smaller than 2 000 nm is used,the linearity of optical tweezers is better;when Duke series sphere with a 800~2 000 nm diameter is adopted,the interchangeability between the same series spheres is better,which will be convenient to calibrate the nanometer optical tweezers;for avoiding Mie resonance,the sphere diameter should be smaller than 2 500 nm.

光纤探针型近场光镊光阱力特性研究

In order to reveal the near-field distribution of electromagnetic field and the axial distribution of trapping force acting on nano-particles located in near-field optical tweezers,and to explore the trapping size,trapping location and trapping stability,the direct calculations of Maxwell stress tensor were solved numerically by using three-dimensional finite difference time domain method without the limitation of dipole approximation.Calculations show that the particle with radius larger than the aperture is pushed away from the tapered metal-coated fiber probe,while it tends to be trapped in larger effective region as the radius becoming smaller.The near-field optical probe can trap and manipulate a nano-particle with tens of nanometres diameter to different positions with different distance from the probe tip.Results of the calculations are found to be helpful for the design and manifacturing of near-field optical tweezers system.

Probing molecular chirality by CD-sensitive dimeric metalloporphyrin hosts

This feature article reviews dimeric metalloporphyrin hosts employed as chirality probes in chiral recognition processes involving synthetic compounds and natural products. Upon formation of a chiral host-guest supramolecular complex between an achiral bis-metalloporphyrin derivative and a chiral non-racemic guest, a CD response occurs in the porphyrin spectral region, which is diagnostic of the guest's absolute configuration. Several bis-porphyrin hosts used in the stereochemical investigation of organic compounds are described and the scope of their application as chirality probes critically assessed. The review encompasses the description of structural features of the host-guest complexes, the nature of the chirality transfer mechanism and the practical application in solving stereochemical problems. In particular, with reference to the method based on bis-porphyrin tweezers, we describe recent advances based on the use of molecular modeling, which have broadened the applicability of the tweezer methodology and allowed extraction of deeper structural information contained in the experimental CD data.

Sipping with Tweezers

Sipping with Tweezers

OK International has introduced the MX-PTZ Precision Tweezer hand-piece for the Metcal MX-500 Soldering/Rework System

OK International has introduced the MX-PTZ Precision Tweezer hand-piece for the Metcal MX-500 Soldering/Rework System

Force probe molecular dynamics simulations.

Many proteins are molecular nano-machines, which perform their biological function via well-coordinated structural transitions. Often, these motions occur on much slower time scales than those accessible to conventional molecular dynamics techniques, which are limited to submicrosecond time scales by current computer technology. This is also true for ligand binding and unbinding reactions. Force probe simulations (or steered molecular dynamics) provide a powerful means to overcome this limitation, and thus to get insight into the atomistic mechanisms that underlie biological functions such as ligand binding. This chapter provides a basic introduction into this method. It further sketches a simple nonequilibrium statistical mechanics treatment that shows how to relate the results of force probe simulations to atomic force microscopy (AFM) or optical tweezer experiments. As an example, enforced unbinding simulations of streptavidin/biotin complexes are detailed.